Marine Day, also known as "Ocean Day" or "Sea Day", is a public holiday in Japan usually celebrated on the third Monday in July. The holiday is to give thanks to the ocean for its bounty and to consider the importance of it to Japan as a maritime nation.
Many people take advantage of the holiday and summer weather to take a beach trip. Other ocean-related festivities are observed as well. The date roughly coincides with the end of the rainy season in much of the Japanese mainland. From Wikipedia
